I don't mean dirt. I mean paint or something. In the USA my oven has white dots on the glass door which are more abundant towards the bottom third and decrease in number at the middle and top. My France oven has thin lines, about 2 cm apart that run horizontally across the whole window.
Do these have a purpose other than to impede my view? Is it like that rule about not looking at the microwave?
The baking show I watch has lovely clear glass oven windows but I'm pretty sure those ovens are totally new whereas my ovens are a few generations old. Are the dots and lines an old school protection for the glass?
Similarly my Teflon pans have a nice decoration on the bottom- Usually in some kind of radiating circle design. Do these have a purpose, to conduct heat? Or is it to remind me which side goes on the burner?